Validate an IBAN structurally before you pay or store it: ISO 7064 mod-97 check digits plus the official per-country length and BBAN layout (~90 countries), returning the bank/branch/account breakdown for FR, DE, ES, IT, BE and NL. Structural validation only — no BIC directory lookup (SWIFT's BIC registry is proprietary) and no proof the account exists. Local, instant. ?attest=1 → Ed25519-signed.